Electric temperature control and fire alarm system



p 8, 1964 H. GJERKEN 3,148,363

ELECTRIC TEMPERATURE CONTROL AND FIRE ALARM SYSTEM Filed 19, 1960 3Sheets-Sheet 1 g 79 3% C /77A O/18A 788 INVENTOR: HAAKON GJERKEN. BY mm$3 ATTORNEYS p 3, 1964 H. GJERKEN 3,148,363

ELECTRIC TEMPERATURE CONTROL AND FIRE ALARM SYSTEM Filed Oct. 19, 1960 3Sheets-Sheet 2 INVENTOR: HAAKON GJERK E N.

BY ML fi ATTORNEYS p 3, 1964 H. GJERKEN 3,148,363

ELECTRIC TEMPERATURE CONTROL AND FIRE ALARM SYSTEM Filed Oct. 19, 1960 5Sheets-Sheet 3 75 76 18 75 76 -I H H F if? i v (72 I v I a 7 7A- 78A18B. 77B- IN V EN TOR:

HAA KON GJERKEN.

RJWLQ 3 ATI'ORNE Y5 United States Patent 3,148,363 ELECTRIC TEP/EERATURECONTROL AND FIRE ALARM SYSTEM Haakon Gjerken, Bergen, Norway, assignorto Gjerken Elektro A/, Bergen, Norway, 2 Norwegian company Filed Get.19, 1960, Ser. No. 63,639 2 Claims. (Cl. 340-227) This invention relatesto fire alarm systems for detecting undue temperature increase atlocations remote from a central station, and for allowing thetransmission of a warning signal indicating the abnormal temperatureincrease.

A disadvantage in known art alarm systems is that they do not,generally, provide any warning preliminary to the fire alarm beingactuated. In many cases, a warning of an increase in temperature of, saytwenty degrees centigrade, may enable a watchman to take care of theabnormal conditions by himself, without the necessity of sending out ageneral warning. However, should the temperature continue to rise, it isdesirable to transmit such general warning, because this condition willalmost inevitably mean outbreak of fire.

Some systems are known in which the temperature at a distant locationmay be sensed and transmitted to a central station. However, suchtemperature sensing systems are complicated and costly, and thus theycannot be used in fire alarm systems in, for instance, factorybuildings, on board ship, and the like, where a large number ofdifferent locations must be watched.

Furthermore, it is desirable to indicate the presence of a fault in thesystems, such as, for example a break in watching circuits, and ashort-circuiting of the system. It is also highly desirable that suchindication of faults or the presence of such faults does not interferewith the transmission of warnings.

It is an object of the present invention to provide a system in which afirst warning is received at the central station upon an increase intemperature to a preselected level, and a second warning is received ifthe temperature is further increased. A further object of the inventionis to provide a system in which such double warning will be received,even when watching circuits of the system are broken or interrupted. Astill further object of the invention is to provide a system in whichsuch interruption is distinctly indicated without interfering with thecorrect receipt and indication of said double warning.

According to the present invention there is provided an electrictemperature control and fire alarm system, comprising an electric D.C.source arranged at a central station, first and second watching conduitsforming closed circuits in parallel from one pole of said source via alocal watching station and back to the other pole of said source, athermosensitive means having first, second and third contact wires, saidfirst contact wire being directly connected to said first watchingconduit, said second contact wire being connected to said secondwatching conduit through a resistor, and said third contact wire beingdirectly connected to said second watching conduit, said thermosensitivemeans being arranged to insulate said first contact wire from saidsecond and third contact wires at normal ambient temperature and toprovide a connection between said first and said second contact wires ata temperature increase to a preselected level and further to provide aconnection between said first and said third contact wires at atemperature increase a second or higher level, watching relay meansarranged on said central station, said watching relay means beingarranged to transmit an indication when a connection is provided betweensaid first and second watching conduits through said resistor and totransmit a fire alarm when a direct connec- ICC tion is provided afterfirst having transmitted said indication.

The invention will now be described further, by way of example only,with reference to the accompanying drawings in which:

FIG. 1 is a simplified sectional view of a temperature indicating deviceincorporated in the system of the pres ent invention.

FIG. 2 is a circuit diagram illustrating the connection of two devicesaccording to FIG. 1 in a system according to the invention.

FIG. 3 is a circuit diagram of the central station in which the desiredchange-over of the watching circuits is effected. The relays are shownin this figure in current free conditions; and

FIG. 4 is a circuit diagram illustrating an arrangement enabling theconnection of telephone equipment into the system.

FIG. 1 shows a thermosensitive device comprising a bulb 10 enclosing acharge 11 of mercury. A first contact wire 12 is melted into the bottomof said bulb whereas a capillary stem 13 protrudes from the upper end ofsaid bulb, a second contact wire 14 being melted into said stem at afirst lower level and a third contact wire 15 being melted into the stemat a higher level. A resistor 16 is permanently coupled between saidwires 14, 15.

Referring now to FIG. 2, the system comprises two permanent watchingconduits 1'7, 18 connected in parallel into the system, the conduit 17extending from a first terminal 17A to an opposite terminal 17B whereasthe conduit 18 extends from a corresponding first terminal 18A to anopposing terminal 18B. The thermosensitive devices 10 are connected intothe system by having one of the contact wires either 12 or 15,preferably the bottom wire 12, connected to the first conduit 17,whereas the other wire 15 is connected to the second conduit 18.

It will appear from the preceding that an increase in temperature willcause the mercury to rise in the capillary stem 13 to provide anelectric connection between the wires 12 and 14, whereby the watchingconduits 17, 18 are connected through the resistor 16. By suitableconnection of the terminals 17A, 17B, 18A and 18B to relays at thecentral station, an indication may be received, said indicationcorresponding to an undue temperature increase somewhere in the system.A further increase in temperature will bring the mercury into contactwith the contact wire 15, thereby short-circuiting is effected betweenthe watching conduits. However, such short-circuiting will be precededby a connection through a resistor 15, so that a suitable selection ofrelay equipment may bring about a sequence leading to the transmissionof fire alarm only in the event that short-circuiting is preceded bysuch connection through a resistor 16, whereas direct short-circuitingof the watching circuits will not effect transmission of fire alarm.

Further, melting contacts 19 are connected in series with the watchingconduits.

By means of two closed watching circuits in parallel a disinterruptionof one or both circuits may be counteracted by connecting the terminals17A and 17B on one side, and the terminals 18A and 1813 on the otherside, whereby one will have a complete circuit which is open at thethermosensitive devices. This circuit will be closed through any of theresistors 16 at a temperature increase in the associated thermosensitivedevice, whereas the circuit is short-circuited at the respectivethermosensitive device by the contact wire 15, when this temperatureincrease is unduly high.

The relay equipment for effecting the desired changeover is shown inFIG. 3. Said relay equipment comprises a first high resistance relay 21of, for instance, 2000 ohms, a second relay 22 of, say, 830 ohms, and athird low resistance relay 23 of, for instance, 60 ohms. Furthermore,the said equipment comprises a fourth relay 24 and an indication relay25 controlling an alarm relay 26. All relays 21 to 26 of the figure areshown in open condition.

In the normal condition, both relays 21 and 22 are closed. The relays 21and 23 are connected in series into the first Watching conduit by aconduit 30 leading from through the winding of the relay 21 to a backcontact 31 of the relay 24 and thence to the terminal 17A, Whereas aconduit 32 leads from the terminal 17E through the winding of the relay23 to the plus lead.

Normally, the relay 21 will be closed while the relay 23 is opened,because the relay 21 is a high resistance relay whereas the relay 23 isa low resistance relay, the voltage drop across the first one beingsufiiciently high to keep the latter one opened.

In this normal condition, the relay 22 is connected into the watchingconduit 18 by a conduit 33 extending from -I) through a back contact 34of the relaly 24 and direct to the terminal 18B, whereas a conduit 35extends from the terminal 18A through a stick contact of the relay 22,through the winding of said relay and from here to a front contact 37 ofthe relay 21, and then to In the normal condition, an increase intemperature will be indicated by closing the relay 23, the connectionbetween the watching circuits through the resistor 16 effecting avoltage increase of sufficient magnitude to close said relay. Thus, afront contact 38 of said relay 23 will be closed to supply currentthrough a conduit 39 to a temperature increase indicator 40 from (-1-)to At a further increase in temperature, a short-circuiting connectionis set up between the watching conduits. Because a positive potential isapplied to the watching conduit 18 from the back contact 34 of the relay24 via the watching conduit 17, the relay 21 will be opened. Said relay21 comprises a back contact 41 connected to a conduit 42 extending fromthe front contact 38 of the relay 23 via a back contact 43 of the relay24, through the winding of the indicating relay 25 and therefrom tothrough a switch 44 serving as restoring switch. In usual manner, thisrelay 25 comprises a front contact 45 for supply of current to the alarmrelay 26 and to a fire indicator 46, said relay further comprising astick contact 25A connected to (-1-) in order to keep the relay 25picked up until restoring the system manually by means of the switch 44.

The preceding represents the mode of operation in a normal condition, inwhich both watching circuits are undisturbed.

When either of the watching circuits 17 or 18 is broken, the relay 22will open, due to said relay 22 being connected in series with thewatching conduit 18 and being charged with current from the frontcontact 37 of the relay 21, which is connected in series with thewatching conduit 17.

However, a conduit 47 extends from the conduit 30 through the winding ofthe relay 21, through a back contact 28 of the relay 22 to the conduit32, which then leads through the winding of the relay 23. Said conduitprovides a connection between the relays 21 and 23, in other wordsbetween the terminals 17A and 17B outside of the watching circuit 17,wherefore said relays 21 and 23 are closed again as in the normalcondition, that is, with the relay 21 normally closed and the relay 23normally opened. Further, the relay 22 comprises a back contact 43applying a positive potential to the terminal 18A through a branchconduit 50.

Because the conditions of indicating an increase in temperature are thatthe relay 23 is closed while the relay 21 is kept in closed condition,one will in this event receive an indication of temperature increase bythe watching conduit 17 being connected to the Watching conduit 18through any one of the resistors 16. As both ends of the watchingconduit 18 are charged with positive potential, any thermosensitivedevice will give such connection regardless of the location of theinterruption if such interruption is present in the watching conduit 18,whereas the cross connection via the conduit 47 of the central stationwill apply this potential to both relays 21 and 23 through the resistor15, regardless of the location of an interruption in the watchingconduit 17.

When short-circuiting as a consequence of a temperature increase leadingto contact of the mercury with the contact wire 15, one will in the samemanner as described above receive a fire alarm, by the relay 21 beingopened and the relay 23 being closed.

For the indication of such interruption a conduit 51 is charged withpositive potential through a back contact 52 of the indicating relay 25,said conduit passing through a back contact 53 of the relay 22 andherefrom to an interruption indicator 54 and therefrom to It should beunderstood that said indicator will be illuminated at an interruption,as the relays 21 and possibly the relay 23 are picked up while the relay22 is dropped away when interuption is present. When fire alarm isindicated, the interruption indicator is disconnected.

When the system is short-circuited, the relays 23 and 24 will be closedand the relay 21 will open. It will appear from the preceding that afirst step in normal operation will involve that the relay 23 is closedwhile the relay 21 is still open, whereupon the relay 21 will open aftera short period, depending upon the rate to increase of the temperature.When short-circuiting the system, the 21 will open, too, while the relay23 is closed, but this relay 21 will proceed substantially at the sametime. By a suitable modification of the relay 23, for instance byshunting a condenser in parallel to its Winding, one may ensure that therelay 21 is opened for a moment before closing up the relay 23. Aconduit 56 extends from via a back contact 57 of the relay 21, a backcontact 53 of the relay 23, through the winding of the relay 24 andherefrom to In other words, the relay 24 will also be closed whenshort-circuiting; from a front contact 59 of said relay a conduit 60extends to an indicator lamp 611 for the indication of short-circuitedconditions by lighting said lamp.

In order to keep the relay 24 closed also after closing the relay 23,same comprises a stick contact 62 applying a positive potential thereto.

The melting contacts 19 referred to previously serve for the indicationof fire alarm in the event of shortcircuiting, said contacts beingarranged to melt at a temperature exceeding that which will giveshort-circuit by the wire 15. Then, the relay 23 will open, too, aconduit 63 supplying current to the relay 25 through a front contact 34of the relay 24 and a back contact 65 of the relay 23.

Because the conduit 60 is charged with current from the back contact 52of the indicator relay 25, the shortcircuiting indicator lamp will bedisconnected at such fire alarm.

It will appear from the preceding that the system will indicateshort-circuiting as well as interruption, but that such indication willnot disturb a fire alarm. When interruption is present in the system,one will also receive information of a temperature increase which mayform a warning, but which is too low to necessitate the transmission ofa fire alarm.

For the restoration of the system, it will be necessary to close therelay 22 and to disconnect the fire alarm relay 25 and the relay 24. Inorder to obtain the reconnection of the relay 22, a reconnecting conduit66 extends from the restoring switch 4-4 to the winding of said relay22, whereby the stick circuit of said relay is restored. As the circuitconnections of the last-mentioned relays extend to the restoring switch,one may by the latter disconnect the relays 24 and 25.

Another advantage in the system described above is that auxiliaryequipment may be incorporated to use the system for simple telephonecalls. Such auxiliary equipment is illustrated in FIG. 4.

Herein, the terminals 17A, 17B, 18A and 13B of the watching conduits areshown. The terminals are connected to two change-over switches 70 and71, arranged to change over the watching conduits 17 and 18 to connectsame to a respective one or" two conduits 72, 73, connected to anamplifier, not shown. At different locations in the circuits,loudspeakers 74 are connected between the conduits 17, 18, insulatedfrom same by condensers 75, 76. Thus, the loudspeakers 74 may formintegral parts of a sound transmitting system of a well known kind. Thecondensers 75, 76 prevent the permanently connected loudspeakers fromhaving any detrimental efiiect on the first alarm system.

What I claim is:

1. An electric temperature control and fire alarm system, comprising anelectric D.C. source arranged at a central station, first and secondwatching conduits forming closed circuits in parallel from one pole ofsaid electric source via a local watching station and back to the otherpole of said source, a thermosensitive means having first, second andthird contact wires, a resistor, said first contact wire being directlyconnected to said first watching conduit, said second contact wire beingconnected to said second watching conduit through said resistor, andsaid third contact wire being directly connected to said second watchingconduit, said thermosensitive means being adapted to insulate said firstcontact wire from said second and third contact wires at normal ambienttemperature and to provide a connection between said first and saidsecond contact wires upon a temperature increase to a first pre-selectedlevel in said thermosensitive means and further to provide a connectionbetween said first and said third contact wires upon a temperatureincrease to a second higher pre-selected level in said thermosensitivemeans, a high resistance relay, and a low resistance relay, said relaysbeing connected in series with said first watching circuit to providethat the first-mentioned relay closes and the second-mentioned relayopens when the temperature in the local watching station is at a normalambient level, and to provide that the second-mentioned relay closes ifthe temperature in said station increases to the firstanentionedpre-selected level, and to provide that the first-mentioned relay opensit the temperature in said station increases to the secondmentionedpie-selected level, said system further comprising a third reiayconnected in series with said second watching conduit, said third relaybeing charged with current through a back contact of said first relayand comprising back contacts for closing said first relay at aninterruption of said first watching conduit and to eifect aninterconnection of said watching conduits at an interruption in each ofsaid watching conduits whereby a single watching circuit is set up whichis interrupted at the thermosensitive means at normal ambienttemperature and is closed thereby at a temperature increase to saidfirst and second order preselected levels.

2. A system according to claim 1, wherein said first and second relaysare connected to said single watching circuit with a connection wherebyclosure at the temperature of said first preselected level will closesaid second relay while keepin said first relay closed while closure atthe temperature of said second preselected level will open said firstrelay.

References Cited in the file of this patent UNITED STATES PATENTS1,097,348 Murray May 19, 1914 2,817,074 Faulkner Dec. 17, 1957 2,827,624Klein Mar. 18, 1958 3,025,504 Ohse Mar. 13, 1962 FOREIGN PATENTS 5,353Great Britain June 7, 1890 133,210 Great Britain Oct. 9, 1919 OTHERREFERENCES Brown et al.: Transistors, a New Class of Relays, in ControlEngineering, December 1956, pp. -76.

1. AN ELECTRIC TEMPERATURE CONTROL AND FIRE ALARM SYSTEM, COMPRISING ANELECTRIC D.C. SOURCE ARRANGED AT A CENTRAL STATION, FIRST AND SECONDWATCHING CONDUITS FORMING CLOSED CIRCUITS IN PARALLEL FROM ONE POLE OFSAID ELECTRIC SOURCE VIA A LOCAL WATCHING STATION AND BACK TO THE OTHERPOLE OF SAID SOURCE, A THERMOSENSITIVE MEANS HAVING FIRST, SECOND ANDTHIRD CONTACT WIRES, A RESISTOR, SAID FIRST CONTACT WIRE BEING DIRECTLYCONNECTED TO SAID FIRST WATCHING CONDUIT, SAID SECOND CONTACT WIRE BEINGCONNECTED TO SAID SECOND WATCHING CONDUIT THROUGH SAID RESISTOR, ANDSAID THIRD CONTACT WIRE BEING DIRECTLY CONNECTED TO SAID SECOND WATCHINGCONDUIT, SAID THERMOSENSITIVE MEANS BEING ADAPTED TO INSULATE SAID FIRSTCONTACT WIRE FROM SAID SECOND AND THIRD CONTACT WIRES AT NORMAL AMBIENTTEMPERATURE AND TO PROVIDE A CONNECTION BETWEEN SAID FIRST AND SAIDSECOND CONTACT WIRES UPON A TEMPERATURE INCREASE TO A FIRST PRE-SELECTEDLEVEL IN SAID THERMOSENSITIVE MEANS AND FURTHER TO PROVIDE A CONNECTIONBETWEEN SAID FIRST AND SAID THIRD CONTACT WIRES UPON A TEMPERATUREINCREASE TO A SECOND HIGHER PRE-SELECTED LEVEL IN SAID THERMOSENSITIVEMEANS, A HIGH RESISTANCE RELAY, AND A LOW RESISTANCE RELAY, SAID RELAYSBEING CONNECTED IN SERIES WITH SAID FIRST WATCHING CIRCUIT TO PROVIDETHAT THE FIRST-MENTIONED RELAY CLOSES AND THE SECOND-MENTIONED RELAYOPENS WHEN THE TEMPERATURE IN THE LOCAL WATCHING STATION IS AT A NORMALAMBIENT LEVEL, AND TO PROVIDE THAT THE SECOND-MENTIONED RELAY CLOSED IFTHE TEMPERATURE IN SAID STATION INCREASES TO THE FIRST-MENTIONEDPRE-SELECTED LEVE, AND TO PROVIDE THAT THE FIRST-MENTIONED RELAY OPENSIF THE TEMPERATURE IN SAID STATION INCREASES TO THE SECONDMENTIONEDPRE-SELECTED LEVEL, SAID SYSTEM FURTHER COMPRISING A THIRD RELAYCONNECTED IN SERIES WITH SAID SECOND WATCHING CONDUIT, SAID THIRD RELAYBEING CHARGED WITH CURRENT THROUGH A BACK CONTACT OF SAID FIRST RELAYAND COMPRISING BACK CONTACTS FOR CLOSING SAID FIRST RELAY AT ANINTERRUPTION OF SAID FIRST WATCHING CONDUIT AND TO EFFECT ANINTERCONNECTION OF SAID WATCHING CONDUITS AT AN INTERRUPTION IN EACH OFSAID WATCHING CONDUITS WHEREBY A SINGLE WATCHING CIRCUIT IS SET UP WHICHIS INTERRUPTED AT THE THERMOSENSITIVE MEANS AT NORMAL AMBIENTTEMPERATURE AND IS CLOSED THEREBY AT A TEMPERATURE INCREASE TO SAIDFIRST AND SECOND ORDER PRESELECTED LEVELS.